1

Load the GESIS Panel data as CSV.
The file format is CSV, accordingly you need the readr library and a function that starts with read_...
library(readr)

gpc <-
  readr::read_csv("./data/ZA5667_v1-0-0_Stata14_synthetic-data.csv")
## 
## -- Column specification --------------------------------------------------------------------------------------------------------------------------
## cols(
##   .default = col_double()
## )
## i Use `spec()` for the full column specifications.

2

Convert the variable sex to a factor.
You can do that while importing the data with the col_types argument or after loading them.
gpc <-
  readr::read_csv(
    "./data/ZA5667_v1-0-0_Stata14_synthetic-data.csv",
    col_types = cols(
      sex = col_factor()
    )
  )

3

Export the dataset as Stata file.
You need the haven::write_dta() function.
gpc <-
  gpc %>% 
  haven::write_dta("./MY_CODE/stata_test_file.dta")

Bonus

Export the dataset in the statistical software format of your choice and, if you have access to this software on your computer, open it for checking.
Again, you need one of th haven::write_...() functions.
gpc <-
  gpc %>% 
  haven::write_dta("./MY_CODE/stata_test_file.sav")